Locking device for seatbelt systems

ABSTRACT

A locking device for seatbelt systems including a fixed locking base, a locking member provided adjacent the fixed locking base and which is movable such that it engages with the locking base, a seatbelt portion which extends between the fixed locking base and the locking member and an arm member which senses the tension on such seatbelt portion and which engages with the locking member such that the locking member is caused to move when the arm member senses a tension on said seatbelt portion which is greater than a predetermined tension and such that the locking member presses the seatbelt portion against the fixed base across its entire width when the locking member is caused to move by the arm member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to seatbelt systems which restrain and protectpassengers during vehicle emergencies and more particularly, to lockingdevices for such seatbelt systems.

2. Prior Art

Generally, seatbelt systems are designed such that one end of thepassenger-restraining belt is retracted with a specific amount of forceon a retractor fastened to the vehicle so that tension is always placedon an intermediate portion of the seatbelt. This tension causes theintermediate portion of the seatbelt to press against the body of thepassenger so that the passenger is in a seatbelt-fastened condition.Furthermore, when the passenger removes the seatbelt, the seatbelt isautomatically retracted and stored.

Recently, however, the low percentage of passenger use has led to theuse of the so-called passive seatbelt systems which force the passengerto wear the seatbelt after entering the vehicle. Such passive seatbeltsystems are arranged such that when the passenger enters the vehicle,the seatbelt is caused to move toward the front of the vehicle so that asufficient space for the passenger to enter or leave the vehicle isformed between the seatbelt and the passenger seat. When the passengerslides his body into the space so that he is seated, the seatbelt iscaused to move back toward the passenger seat. Accordingly, the space infront of the passenger contracts so that an intermediate portion of theseatbelt is fastened around the passenger thereby automatically placingthe passenger in a seatbelt fastened condition. If the vehicle isinvolved in an emergency such as a collision and the seatbelt has beenfastened around the passenger, a pawl actuated by an inertia sensor iscaused to engage with ratchet wheels fastened to the seatbelt retractorshaft inside the retractor so that the rotation of the retractor shaftin the direction of seatbelt extension is abruptly stopped. Accordingly,extension of the webbing is prevented and the passenger is restrained.

In such passive seatbelt systems, however, the seatbelt is caused tomove a great distance when the passenger enters or leaves the vehicle.As a result, the amount of seatbelt retracted on the retractor isextremely large in comparison to the amount retracted in an ordinaryseatbelt systems. For this reason, the webbing retracted on theretractor shaft continues to be extended even after the rotation of theretractor shaft in the dirction of the seatbelt extension has beenstopped during a vehicle emergency. The extension continues until theseatbelt is tightly wound on the retractor shaft. In other words, theseatbelt is tightened on the retractor shaft so that a length ofseatbelt corresponding to the amount by which the seatbelt is tightenedis continued to be extended from the retractor. As a result, suchpassive seatbelt systems suffer from a drawback of incomplete passengerrestraint.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of the present invention to providea seatbelt locking device for seatbelt systems which makes it possibleto securely lock an intermediate portion of the passenger restrainingseatbelt so that the passenger is immediately and securely restrainedduring an emergency.

The above mentioned objects are accomplished by a unique locking devicefor seatbelt system. The locking device includes a fixed locking base, alocking member provided adjacent the fixed locking base and which ismovable such that it engages with the locking base, a seatbelt portionwhich extends between the fixed locking base and the locking member anda arm member which senses the tension on the seatbelt portion and whichengages with the locking member such that the locking member is causedto move when the arm member senses a tension on such seatbelt portionwhich is greater than a predetermined tension and such that the lockingmember presses the seatbelt portion against the fixed base across itsentire length when the locking member moves.

BRIEF DESCRIPTION OF THE DRAWINGS

Above-mentioned features and objects of the present invention willbecome more apparent with reference to the following description takenin conjunction with the accompanying drawings wherein like referencenumerals denote like elements, in which:

FIG. 1 is a cross sectional view illustrating a first embodiment of theseatbelt locking device in accordance with the teachings of the presentinvention;

FIG. 2 is an oblique view of the embodiment of FIG. 1;

FIG. 3 is a magnified view of the essential parts of the embodiment ofFIG. 1;

FIG. 4 is an oblique view of FIG. 3;

FIG. 5 is a cross sectional view along the line V--V in FIG. 3;

FIG. 6 is a magnified cross sectional view which illustrates theessential parts of the second embodiment of the seatbelt locking devicein accordance with the teachings of the present invention;

FIG. 7 is an oblique view of FIG. 6; and

FIG. 8 is a cross sectional view along the line VIII--VIII in FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

Referring more particularly to the drawings, shown in FIGS. 1 through 5is a first embodiment of the seatbelt locking device in accordance withthe teachings of the present invention. In this embodiment, the seatbeltlocking device is provided with a retractor 10. The retractor 10includes a retractor shaft 14 supported on a frame 12 which is made bybending a metal plate into roughly a U-shape. One end of the passengerrestraining seatbelt 16 is wound around the retractor shaft 14.Furthermore, this end of the seatbelt 16 is secured to the retractorshaft 14 by being passed through and around a C-shaped stopper 18. Inaddition, a spring driven retractor mechanism 20 is installed betweenthe retractor shaft 14 and the frame 12 on the portion of the retractorshaft 14 which projects from the frame 12. This mechanism 20 powers theretractor shaft 14 in the direction indicated by the arrow A such thatthe seatbelt 16 is retracted. Accordingly, the passenger can donseatbelt 16 by pulling the seatbelt 16 in the direction indicated by thearrow B against the force of the spring-driven retractor mechanism 20.

Furthermore, a bracket 22 is installed across the bottom of the frame 12and a pendulum 24 suspended from the bracket 22. A pawl 26, supported sothat it is free to swing toward the bracket 22, is installed above thependulum 24. During a vehicular emergency, the pawl 26 is pushed upwardby the pendulum 24 which swings when it detects acceleration of thevehilce. As a result, the pawl 26 engages with a ratchet wheel 28attained to the retractor shaft 14 so that the rotation of the retractorwheel 28 and the retractor shaft 14 in the direction of seatbeltextension is stopped.

The locking device 30 provided by this invention is attached to theframe 12. The locking device 30 includes a fixed base 32, a lockingmember 34 and an arm 36.

The fixed base 32 is made from plastic, but the fixed base 32 could alsobe made from metal. One end of the fixed base 32 is fastened to theframe 12 by pressing the tip of the end through a fastening hole 38drilled in the frame 12 so that the tip is locked in the fastening hole38. A wavy surface 40 is formed on the other side of the fixed base 32and this surface 40 forms a locking surface for the seatbelt 16.

Furthermore, a wavy surface 42 is formed on one surface of the lockingmember 34 facing the wavy surface 40 of the fixed base 32. Ahemispherical projection 44 projects from the opposite surface of thelocking member 34. The locking member 34 is engaged on both sides by theends of a leaf spring 48 whose other end is fastened to the frame 12 byrivets 46. As a result, the locking member 34 is driven in a directionwhich separates it from the fixed base 32, i.e., in a direction whichcauses both of the wavy surfaces 40 and 42 to be separated from eachother.

A pin 50 is passed through an intermediate part of the arm 36. The pin50 is supported on the frame 12 and the arm 36 is provided on the pin 50such that it can pivot relative to the frame 12. The tip of one end ofthe arm 36 has a rounded contact surface 52 and this contact surface 52contacts an intermediate portion of the seatbelt 16. A hemisphericalrecess 54 is formed at the other end of the arm 36. This recess 54engages with the hemispherical projection 44 on the locking member 34.The hemispherical projection 44 and the hemispherical recess 54 causetorque on the arm 36 to be transmitted to the locking part 34 such thatthe locking part 34 is caused to approach the fixed base 32. Thecoupling device formed by the hemispherical projection 44 and thehemispherical recess 54 allows the locking part 34 to rotate about themajor axis (line L--L) and the minor axis (line N--N) of the seatbelt16.

Thus, the locking device 30 is fastened to a portion of the frame 12.The seatbelt 16 extending from the retractor shaft 14 passes between thelocking member 34 and the fixed base 32 after being turned around aroller 58 which is supported on the frame 12 by means of a pin 56. Theseatbelt 16 is then turned around the contact surface 52 on the arm 36and extends in a direction of the passenger seat. The seatbelt retractor10 is further fastened to the motor vehicle 60 by means of the fasteningbolt 62.

In operation, the retracting force constantly applied to the retractingshaft 14 by the spring-driven retractor mechanism 20. Accordingly, thereis a constant retracting tension acting on the seatbelt 16 extendingfrom the retractor shaft 14. In order to don the seatbelt 16, thepassenger pulls the seatbelt 16 against the retracting force of thespring-driven retractor mechanism 20. When the seatbelt 16 is thuspulled, it moves in the direction indicated by the arrow B such that theseatbelt 16 can be donned by the passenger. In this case the retractingforce on the spring-driven retractor mechanism 20 gradually increases asthe seatbelt 16 is extended. As a result, the arm 36 attempts to rotatein a counterclockwise direction about the pin 50. However, the leafspring 48 causes the locking member 34 to oppose the rotational force.Accordingly, the locking member 34 is maintained at an appropriatedistance from the fixed base 32.

When the vehicle is involved in an emergency such as a collision, thepassenger is violently thrown in the direction of vehicle impact. As aresult, the seatbelt 16 is extended from the retractor 10 and theseatbelt 16 begins to move rapidly in the direction indicated by thearrow B. However, the pendulum 24 detects the acceleration of thevehicle and swings, thereby pushing the pawl 26 upwardly such that thepawl 26 engages with the ratchet wheel 28 to thereby stop rotation ofthe retractor shaft 14 in the direction of seatbelt 16 extension. Thiscauses an abrupt increase in the tension on the seatbelt 16. As aresult, torque is caused to be applied to arm 36 which is in contactwith the seatbelt 16 via the contact surface 52. Accordingly, arm 36rotates in a counterclockwise direction about the pin 50 with a greatforce. Accordingly, torque of the arm 36 causes the locking member 32 tomove against the force of the leaf spring 48 such that the seatbelt 16is securely clamped between the wavy surfaces 40 and 42.

Referring to FIG. 5, the following is the description of the situationwherein errors have been committed in the installation of the variousparts making up the locking device 30. For example, in the case wherethe pin 50 of the arm 36 is installed in the frame 12 such that the axisof the pin 50 has an installation error of angle θ, the torque of thearm 36 acting on the locking member 34 is inclined as indicated by arrowC. If the locking member 34 similarly moves in the direction indicatedby the arrow C and clamps the webbing between itself and the fixed base34, the clamping force will act only on the portion of the width of theseatbelt 16. As a result, there is a danger that the seatbelt 16 will becut by the clamping force.

In this embodiment, however, the torque of the arm 36 is transmitted tothe locking member 34 via the hemispherical recess 54 and thehemispherical projection 44. As a result, the locking member 34 is ableto rotate about both the major and minor axes of the web of the seatbelt16. Accordingly, installation error of the arm 36 relative to the frame12 is corrected. Therefore, the locking member 34 clamps the seatbelt 16perpendicular to the surface of the seatbelt 16 as indicated by thearrow D, i.e. the seatbelt 16 is clamped by a uniform clamping forceapplied across the entire width of the seatbelt 16. As a result,movement of the seatbelt 16 in the direction of the extension issecurely prevented. As a result of the seatbelt 16 being blocked by thelocking device 30, further tension on the seatbelt 16 is not transmittedto the retractor shaft 14. Therefore, there is no danger that theseatbelt 16 will be extended from the retractor 10 due to the tighteningof the seatbelt 16 on the retractor shaft 14 as in conventional devices.Therefore, a passenger wearing the seatbelt 16 is securely restrained.

Referring to FIGS. 6 through 8 shown therein is a second embodiment of alocking device in accordance with the teachings of the presentinvention. In this second embodiment, another type of coupling devicefor transmitting the torque from the arm 36A to the locking part 34A isillustrated and described.

In this second embodiment, extensions 64 are formed on both sides of thelocking member 34A. These extensions 64 are respectively inserted intoguide windows 66 drilled in the frame 12A such that the locking member34A can approach and move away from a fixed base 32A. In this case, aconsiderable amount of space is provided between the extensions 64 andthe guide windows 66. Thus, if necessary, the locking member 34A canmove in the directions of the major axis and the minor axis of theseatbelt 16. Furthermore, a bracket 68 is attached to the top of thelocking member 34A. This bracket 68 passes through cutout slot 70 formedin one end of the arm 36A. A tension coil spring 74 is installed betweenthe bracket 68 and a support 72 provided on the frame 12A such that thelocking member 34A is driven in the direction which separates from thefixed base 32A. In this second embodiment, the force of the tension coilspring 74 causes a space to be maintained between the locking member 34Aand the fixed base 32A under normal vehicle operational conditions sothat the seatbelt 16 can be extended from the retractor 10.

In operation during a vehicular emergency, the arm 36A detects thetension on the seatbelt 16 and causes the locking member 34A to approachthe fixed base 32A. Accordingly, an intermediate portion of the seatbelt16 is securely locked and the passenger is securely restrained such thatthe safety of the passenger is insured. Furthermore, the locking member34A supported on the frame 12A such that it can move in the direction ofthe major and minor axes of the seatbelt 16. As a result, in cases wherethe locking device 30A has an installation error relative to the frame12A (as shown in FIG. 8), the locking member 34A can rotateappropriately about the major and minor axis of the seatbelt 16 suchthat a broad area of the intermediate portion of the seatbelt isclamped. Accordingly, the intermediate portion of the seatbelt 16 can besecurely clamped and locked and accidents leading to the breakage of theintermediate portion of the seatbelt resulting from the clamping of thenarrow area of the seatbelt 16 can elliminated.

As is described above, the seatbelt locking device 30 provided by thisinvention makes it possible to lock an intermediate portion of theseatbelt during a vehicular emergency. Accordingly, this invention isable to prevent the tightening of the seatbelt on the retractor shaftwhich is unavoidable in conventional designs. As a result, this seatbeltlocking device is able to restrain the passenger securely. Inparticular, the seatbelt lock provided by this invention clamps a broadarea of the seatbelt. Therefore, this invention possesses the superioradvantage of being able to eliminate accidents in which the webbing isbroken by the clamping force of a locking device.

It should be also apparent that the locking device need not be providedwithin the retractor itself and could be provided at some locationremote from the retractor.

It should be apparent to those skilled in the art that the abovedescribed embodiment is merely illustrative of but a few of the manypossible specific embodiments which represents the application of theprinciples of the present invention. Numerous and varied otherarrangements can be readily devised by those skilled in the art withoutdeparting from the spirit and scope of the invention.

We claim:
 1. A locking device for a seatbelt system comprising:a fixedbase having a wavy surface; a locking part having a wavy surfaceadjacent to said fixed base which under ordinary conditions is separatedfrom the fixed base so that a passsenger-restraining seatbelt is allowedto pass freely between the locking part and the fixed base, said wavysurfaces of said fixed base and said locking part cooperating such thatwhen said wavy surfaces approach each other, the seatbelt passingbetween said wavy surfaces is formed into a wavy shape to thereby clampthe seatbelt between said locking part and the fixed base when saidlocking part approaches said fixed base; an arm, one end of whichcontacts the seatbelt and which causes the locking part to approach thefixed base when the tension on the seatbelt exceeds a given value; and acoupling device which is installed between the arm and locking part andwhich will allow the locking part to rotate about a major axis of theseatbelt whereby the locking part is caused to press the seatbeltagainst the fixed base across the entire width of said seatbelt, saidcoupling device comprising a biasing means for biasing said locking partinto contact with said arm.
 2. A locking device for seatbelt systems asdefined in claim 1, wherein said locking part is further coupled to saidcoupling device such that it also allows the locking part to rotateabout the minor axis of the seatbelt whereby the locking part is causedto press the seatbelt against the fixed base along a considerable lengthof said seatbelt.
 3. A locking device for seatbelt systems as defined inclaim 1, wherein the locking part is driven by an elastic part in adirection which separates said locking part from the fixed base.
 4. Alocking device for seatbelt systems as defined in claim 1, wherein thecoupling device is located at the opposite end of the arm, relative tothe center of rotation of said arm from the end of said arm whichcontacts the seatbelt.
 5. A locking device for seatbelt systems asdefined in claims 1 or 2, wherein the coupling device comprises ahemispherical projection installed on the back of the locking part and ahemispherical recess which is installed in the arm and into which thehemispherical projection is inserted.
 6. A locking device for seatbeltsystems as defined in claims 1 or 2, wherein the fixed base is attachedto a frame which supports a seatbelt retractor shaft and the arm issupported on this frame.
 7. A locking device for seatbelt systems asdefined in claim 6, wherein the fixed base and locking part are bothinstalled on the frame which supports the passenger-restraining seatbeltretractor shaft and extensions provided on the locking part are insertedinto guide windows drilled in the frame such that the locking part has aspecified amount of freedom of movement.
 8. A locking device forseatbelt systems as defined in claim 6, wherein a ratchet wheel isattached to the retractor shaft and said ratchet wheel is engaged by apawl which is caused to incline when it detects vehicle acceleration sothat extension of the seatbelt is stopped during a vehicle emergency. 9.A locking device for seatbelt systems as defined in claim 7, wherein aratchet wheel is attached to the retractor shaft and said ratchet wheelis engaged by a pawl which is caused to incline when it detects vehicleacceleration so that extension of the seatbelt is stopped during avehicle emergency.